Apparatus for radiation promoted processes



July 18, 1961 A. D. SUTTLE, JR 2,992,980

APPARATUS FOR RADIATION PROMOTED PROCESSES Filed May 16, 1957 4 32 42OQQQIIOIOQOI V j j INVENTOR.

6 4% N ANDREW D. SUTTLE JR., 20 I6 20 BYafl/jfl) FIG. 3.

ATTORNEY.

Patented July 18,1961

APPARATUS FOR RADIATION PROMOTED PROCESSES Andrew D. Suttle, J12,Baytown, Tex., assignors by mesne assignments, to Esso Research andEngineering Company, Elizabeth, N.J., a corporation of Delaware FiledMay 16, 1957, Ser. No. 659,639

- 9 Claims. (Cl. 204193) This invention concerns a technique forcarrying out chemical processes which are promoted by radiation. Inparticular, the invention concerns a reactor employing beta emittingmaterial as the radiation source. It is a particular feature of thisinvention to provide a reactor of the character indicated in which thebeta emitting material is supported completely within the reactor in theform of thin bodies of the material.

This application is a' continuation-impart of application Serial No.460,868, filed October 7, 1954, for Andrew D. Suttle, Jr., entitledChemical Reactor for Radiation Promoted Processes, now abandoned.

.At the present time, it is known that many chemical conversion.reactions such as isomerization, sullfochlorination, polymerization,depolymerization, etc. can be promoted by subjecting the material ormaterials to be converted to irradiation by high energy electrons. Ingeneral, electron bombardment of compounds such as hydrocarbons'resultsin the formation of electrons, ions, tree radicals, and excitedmolecules and atoms. These products of electron bombardment areexceedingly reactive, resulting in the formation of conversion productsin reaction times which may well be less than one second.Polymerization, dimerization, and isomerization processes may beidentified as exemplary.

Heretofore the possibility of commercially conducting such radiationpromoted processes has appeared remote. This is due in part to thecomplexity of obtaining a suitable source of high energy electrons.

For a number of reasons it is not practical to employ electrongenerators such as the Van de Graafi generator, linear accelerators, orthe betatron. Aside from the expense of such generators, practicaldifiiculties are encountered in transmitting the electrons produced.into a reaction zone. This can ordinarily only be accomplished bypositioning the material to be converted in a reactor provided withwindows of a substance through which .the electrons can penetrate. Thenecessity of providing radiation transparent material in such reactorsis a severe practical limitation to the possibilities of use. This isparticularly true since for particular conversion processes it may bedesirable to use'temperatures ranging all the way from that of liquidnitrogen upwardly to 800 C. or higher. desirable to employ extremelyhigh pressures. Clearly, it is quite diflicult to provide a reactor ofthe character indicated equipped with radiation transparent windowswhich can be used under such extreme conditions. This istrue in partsince attempts to design such reactors obviate the purpose intended byrequiring windows of sutficient thickness and strength so thatabsorption of radiation passing therethrough becomes prohibitive. It isagain apparent that any design which can be made seriously, limits thequantity of radiation which may be introduced into the reaction zonesince it is not practical to entirely bound a reaction zone with theradiation transparent material.

In accordance with the present invention, a radiation promoting reactoris provided which contains thin bodies of beta emitting materialsupported completely a reactor. The possibility of using beta emittingmaterial is particularly attractive because of the availability of suchmaterial as the fission products of atomic reac- Simil-arly, it isfrequently tions. As is generally known, fission products are nowproduced in suflicient quantities so that these products therefore toprovide a practical use for fission products in promoting chemicalreactions.

The particular beta emitting material to be employed may be selectedfrom a wide variety of radioactive isotopes such as St, Sr Y Y Ru Ru R11and Ce --Pr For the purposes of this invention, it will of course bedesirable to select particular beta emitting isotopes, such as thoseidentified, which have a long life. a half life of at least thirty days.Actually, beta emitting radioactive isotopes can be selected having ahalf life of approximately 25 years.

It is one of the advantages of using beta emitting materials inaccordance with this invention that the reactor in which these materialsare employed requires little shielding. This is particularly true withrespect to hydrocarbon reactants and other reactants composed of atomsof comparatively low atomic number (e.g., about 20 or less) in that fewbremsstrahlung are produced. This is due to the fact that beta emissionhas a relatively short range. In particular the range of beta radiationis a great deal shorter than that of gamma radiation so that theproblems of handling these materials safely. are considerablysimplified. The range of beta radiation is of the order of approximatelyone gram per square centimeter.

While the short range of beta radiation is a real advantage as regardsthe shielding of reactors using beta emitters, at the same time theshort range of beta radiation imposes real problems in designing asuitable reactor using beta emitting material. It would not bepractical, for example, to attempt to position the beta emittingmaterial behind the ordinary windows supplied in the walls of radiationpromoting reactors. For one thing, the thickness of the windowsrequired, since they make up a portion of the reactor itself and mustwithstand the reaction pressures, would be prohibitive, resulting inabsorption of substantialportions of the beta energy because of theshort range of this energy. Again, it would be impractical to positionsufficient thicknesses of beta emitting material behind such localizedwindows so as to attain high intensity levels within the reactor, muchof the radiation would then be absorbed by the beta emitting materialitself.

In considering these factors, it is the particular concept of thisinvention to employ the beta emitting material in the form of thinbodies such as sheets, films, screens, etc. These bodies are positionedcompletely within the reactor vessel. Since the thin bodies of emittingmaterial are positioned completely within the reactor, it is unnecessaryto fabricate these thin bodies of the strength which would be requiredwere they to be used as elements of the reactor wal-ls. Again, thisprovision avoids the difliculties normally encountered in constructing areactor of two or more difierent materials due to the temperatureexpansion problems and so on.

The particular manner in which the thin bodies of the beta emittingmaterial are fabricated depends in part upon the particular betaemitting isotope which is chosen. While it would appear desirable tofabricate these sheets consisting of pure beta emitting material this isnot ordinarily practical. For one thing, beta emitting isotopes have avariety of physical properties but often are not ordinarily suitable forfabrication into the form of self-supporting, thin sheets. Even in thecase of those metallic beta emitters which might be employed, adifficulty encountered is the reactivity of these materials in theordinary reactant system. Consequently, while it is In general, amaterial will be chosen having characteristics.

within the scope of this invention to employ thin bodies of materialfabricated solely from the beta emitting material this is not ordinarilycarried out.

. In the preferred form of this invention, the isotope constituting thebeta em-titing material is formed into a sheet which is sandwichedbetween thin sheets of beta transparent metal. In general, thesupporting sheets of metal between which the beta emitting material ispositioned are about 0.001 inch thickto about 0.1 of an inch thick. Theparticular metal composing the supporting metal sheets is chosen withregard to the reactants which are to be processed. It is clearlynecessary to select the metal so that it will not be attackedor reactivewith the particular reaction system. Inaddition, it is necessary toselect the metals in view of their radiation transmitting In thisconnection, among the metals which can be employed as the, supportingsheets, aluminum, stainless steel, and beryllium are particularlyattractive for use. Stainless steel is particularly useful sincethis-metal can be fabricated as an extremely thin sheet having athickness ofabout 3 to thousandths of an inch while still providing allthe strength required for the purposes of this invention. Again,stainless steel is normally non-reactive in most reaction systems towhich this invention has application.

While as indicated, the preferred technique of this invention requiresthe disposition of the beta emitting material between thin sheets ofmetals, it is within the.

scope of this invention to plate supporting sheets, screens, etc. withthe beta emittingmaterial or to alloy the emitting material in asupporting metal sheet, screen, etc.

In order to show the practical applications of this invention, referencewill be made to the accompanying drawings in which:

FIG. 1 illustrates in cross-sectional elevational view a reactorconstructed in accordance with this invention;

FIG. 2 diagrammatically illustrates a sheet of .theemitting material;

FIG. 3 illustrates a modified sheet construrction which may be employed;

FIG. 4 illustrates in fragmentary cross-sectional elevationa-l view amodified reactor of the present invention;

FIG. 5 is an elevational view of an element of the reactor of FIG. 4;and

FIG. 6 is a cross-sectional view of the reactor of FIG. 4. taken alongthe lines 66.

In FIG. 1, the numeral 1 designates a reactor shell. This reactor shellmay be constructed of any desired type of material in any design so asto provide the necessary structural requirements ofthe particularreaction system. Transversely disposed across reactor '1 are upper andlower support =grids 2 and 3. As illustrated, these are perforated withperforations 4 so that reactants may fiow readily through these supportmembers. The sheets of beta emitting materials are disposed between thesupporting members 2 and 3. These sheets of beta emitting material areindicated by numerals 8, 9, 10 and 11. While these sheets areillustrated as being parallel to each other, it is apparent that avariety of arrangements for these sheets could be made. For example, thesheets of beta emitting material could be arranged as concentriccylinders within the reactor, as a continuous spiral of materialarranged within the reactor or in other desired forms. It is also to beunderstood, of course, that forms other than sheets can be employed ifdesired including screens, ribbons, tubes or rods. It is particularlydesired to position the sheets of radiation emitting materialsufliciently within the reactor so as to be spaced a substantialdistance from the walls of the reactor. A

suitable spacing is about 2 or 3 to 5 ,half thicknesses of the radiationemitting material from the wall. This provision can be followedso as toeliminate any need for particular shielding precautions of the reactoras a whole.

The spacing between the sheets of beta emitting material will bedetermined in large part by the reaction system in which the reactor isto be employed. For example, the range of beta radiation in a liquid issubstantially less than that in a gas. Consequently, in the case inwhich a liquid phase reaction is carried out in the reactor,,it isdesirable to space the sheets of beta emitting material relatively closetogether, e.g., between 1 mm. and 5 cm. apart. Again, the spacing of thesheets of radioactive material will depend in part upon the particularreaction as regards the. intensities of radiation required to suitablyeffect conversion. Greater spacings can be employed for those reactionswhich require lower levels of energy for conversion.

In order to diagrammatically indicate the use of reactor 1, a feed inletline 6 is shown at the bottom of the reactor together with a productwithdrawal line 7 at the top of the reactor. Thus, as illustrated, feedreactants can be brought into the bottom of the reactor and will bedistributed by the supporting grid or plate 3 through the perforations 4so as to pass between the sheets of radioactive emitting material. Theproducts of this conversion will be passed through perforations 4 of theupper supporting grid 2 and can be removed from the vessel through line7.

Referring now to FIG. 2, one of the methods of suitably fabricating thesheets of beta emitting material used in the apparatus of FIG. 1 isillustrated. In FIG. 2 the sandwich-type construction formerly describedis illustrated. In this arrangement a central layer of beta emittingmaterial identified by numeral 12 is positioned between two thin sheetsof a supporting metal. This layer will be no more than 2 halfthicknesses of the beta emit-- ting material thick providing a thicknessranging up to about 0.1 of an inch. The supporting metal sheets areidentified by numbers 13 and 14. The fabrication technique of FIG. 2 is,of course, particularly adapted to the case in which the beta emittingmaterial can be fabricated as a sheet material. If this is not the case,the

many alternative ways in which the radiation emitting material may besupported is illustrated. In the arrangement of FIG. 3, two sheets ofsandwiching metals 15 and 16 are again employed. However, in thisparticular arrangement at least one of these sheets of metals isprovided with stilfening ribs. These stiifening ribs may be madeintegral with the sheet of metal itself as illustrated in the drawing soas to have the corrugations or strengthening elements designated bynumber 20. Alternatively, of course, strengthening elements can bewelded to, bolted to or otherwise fixed to the metals to bestrengthened. In the fabrication method of FIG. 3 due to the absorptionof radiation which would occur by the strengthening members, it isdesirable that the radioactive material be distributed at centralizedlocations between the strengthening members. This is illustrated in thedrawing where localized concentrations of radioactive material,identified by numerals 17, are shown. Preferably the volume between thelocalized portions of radioactive material is evacuated since thiseliminates useless absorption ofv energy by filler material which canalternatively be employed. Clamping and sealing members 18 are providedabout the periphery of the sheets.

As described, this invention entails the use of thin bodies of betaemitting material. This may be achieved in a wide variety of methods. Apreferred technique concerns the sandwiching or encapsulating of theemitting material between thicknesses of a supporting material. By theprovisions of this invention it becomes practical to expose reactants toa large area of emitting surface.

With reference to FIG. 4, there is shown a fragmentary elevationalview-of a modified reactor of the present.

invention wherein screens of a beta emitting material are and a reactionproduct outlet line 7 or a plurality of such lines. The interior of theshell 1' is provided with a plurality of longitudinally spaced lateralsupport means such as support rings 30 adapted to support transverselydisposed bodies of beta emitting materials such as members containingscreens 32 of a beta emitting material such as Ruthenium 106.

The screen members 32 may be of any suitable construction. Thus, forexample, as shown in FIG. 5, a screen 32 of Ruthenium 106 or a pluralityof such screens may be supported by an inner support ring 36 and securedthereon by means of an outer retaining ring 38. In order to provide forthe most eflicient use of the beta emitting material, it is preferablethat the screen be composed of comparatively fine wires of about 0.002to 0.010 cm. diameter and have a mesh width of about 1 to 3 halfthicknesses of the beta emitting material.

With a reactor having the construction shown in FIG. 4, it is possibleto provide for highly agitated flow of the reactants through thereactor.

In situations wherein highly exothermic reactions are involved, such asin the sulfochlorination of hydrocarbons, the heat of reaction may beremoved by jacketing the reactor in any suitable manner such as with ajacket 31 and flowing a cooling medium through the jacket 31. As asupplementary or alternate cooling means there may be provided a coolingcoil 40 intermediate one or more pairs of screen members 32. Thus, as isshown more clearly in FIG. 6, the cooling coil 40 may comprise an inletline 42 fluidly interconnected with a plurality of branch coil lines 44,the lines 44 being fluidly interconnected with a discharge line 46.

When it is desired to supply heat to the shell 1', the jacket 31 and/orthe coil 40 may be utilized as a heating means.

The invention will be further illustrated by the following specificexamples which are given by way of illustration and not as limitationson the scope of this invention.

Example 1 Flow a mixture of equimolar amounts of sulfur dioxide,chlorine and n-heptane cooled to a temperature of about 0 C. through areactor constructed in the manner shown shown in FIG. 4 whilemaintaining the reaction mixture below the boiling point of then-heptane by passing a suitable coolant (e.g., ice Water) throughcooling coils 40. The reactor 1' may have an internal diameter of about50 cm., an overall length of about 10 to 100 cm., and

contain a total of about 3 to 20 of the ruthenium screen members 32whereby, with a react-ants flow rate of about 1 to 10 liters per minute,about 50 curies of beta radiation per mol of reactants present isprovided. The product comprises unreacted heptane, chlorine and sulfurdioxide, together with heptane sulfonyl chloride and heptyl chlorides,the heptane sulfonyl chloride being obtained in about 80% yield.

Example II An ethylene polymerization catalyst of the type disclosed andclaimed in copending Schutze et al. application S.N. 538,518, filedOctober 4, 1955, now abandoned, is prepared by flowing a 3 volumepercent solution of titanium tetrachloride in n-heptane at a temperatureof about +10 C. through a reactor constructed in the manner shown inFIG. 1, the reactor being provided with sandwich-type sheets as shown inFIG. 2 containing a central layer of Sr Y positioned between stainlesssteel sheets. Thus, there may be used a total of 10 -10 curies of Sr "-Yfabricated into a plurality of sheets having a thickness of 0.2 to 2half thicknesses of Y,

6 such sheets being encased between stainless'steel support ing sheetshaving a thickness of about 0.01 to 0.2 half thickness of Y. The rate offlow of the heptane solution through the reactor With a residence timeof 5 to 10 minutes should be sufiicient to provide for about 3X10 curiesof beta radiationper gram of TiCl whereby the titanium tetrachloride isreduced to an activated form of titanium trichloride useful for the lowtemperature polymerization of ethylene.

What is claimed is:

1. Apparatus for conducting a beta-radiation promoted process comprisinga closed, essentially unshielded housing vessel adapted to sustain thetemperatures and pressures required for the process, means forintroducing and removing reactants and products from the reactor, a thinbody of metal positioned within said vessel comprising, as the soleradioactive material, a metal emitting substantially exclusively highenergy beta radiation and means for supporting said thin body ofmaterial within said vessel at a distance from said housing greater thanthe beta radiation range of said thin body of metal, said thin body ofmetal having a thickness of not more than about two half-thicknesses ofsaid beta-emitting metal.

2. The apparatus defined by claim 1 in which said means for supportingthe emitting material comprises means to suport thin solid sheets of theemitting material.

3. The apparatus defined =by claim 1 in which said means for supportingthe thin film of emitting material comprises a pair of radiationtransparent metal sheets between which the beta emitting material ispositioned.

4. The apparatus defined by claim 1 in which the said means forsupporting the beta emitting material comprises thin metallic plates inwhich the said beta emitting material is alloyed.

5. The apparatus defined by claim 1 in which the said means forsupporting a thin film of beta emitting material comprises metallicsheets including stiflzening members spaced along at least one side ofeach of said sheets and including provision for concentrating andlocalizing the position of the beta emitting material between saidstifiening members.

6. The apparatus defined by claim 1 in which the beta emitting materialis a sheet of Sr ---Y having a thickness of 0.2 to 2 half thicknesses ofY and wherein the means for supporting the said sheet comprises a pairof stainless steel sheets having a thickness within the range of about 3to 5 thousanths of an inch between which said sheet is positioned.

7. Apparatus for conducting radiation promoted processes comprising aclosed, substantially unshielded elongate housing adapted to sustain thetemperatures and pressures required for the process, a plurality ofscreen members comprising a body of material emitting substantiallyexclusively high energy beta radiation, means for supporting saidscreens in spaced relationship to each other transversely of the lengthof said housing, means adacent one end of said housing for introducingreactants, and means adjacent the other end of said housing for removingreactants and reation products, said screens having a diameter withinthe range of 0.002 to about 0.10 centimeters and having a mesh widthwithin the range of about 1 to 3 half thicknesses of the beta emittingmaterial.

8. A device as in claim 7 including means for regulating reactiontemperature parallel with and intermediate at least a pair of adacentscreens in said reactor.

9. A device as in claim 7 wherein the beta emitting material isruthenium.

References Cited in the file of this patent UNITED STATES PATENTS1,627,938 Tingley May 10, 1927 (Other references on following page) 7UNITED STATES PATENTS Fischer June 25, 1929 McCray Feb. 19,. 1935'Fischer Aug. 10, 1943 Pregel July 10, 1951 Schultz et a1. Nov. 13, 1951

1. APPARATUS FOR CONDUCTING A BETA-RADIATION PROMOTED PROCESS COMPRISINGA CLOSED, ESSENTIALLY UNSHIELD HOUSING VESSEL ADAPTED TO SUSTAIN THETEMPERATURES AND PRESSURES REQUIRED FOR THE PROCESS, MEANS FORINTRODUCING AND REMOVING REACTANTS AND PRODUCTS FROM THE REACTOR, A THINBODY OF METAL POSITIONED WITHIN SAID VESSEL COMPRISING, AS THE SOLERADIOACTIVE MATERIAL, A METAL EMITTING SUBSTANTIALLY EXCLUSIVELY HIGHENERGY BETA RADIATION AND MEANS FOR SUPPORTING SAID THIN BODY OFMATERIAL WITHIN SAID VESSEL AT A DISTANCE FROM SAID HOUSING GREATER THAN